Regenerative medicine holds the potential to create living, functional cells and tissues which can be used to repair or replace those that have suffered irreparable damage due to disease, age, traumatic injury, or congenital defects. Although regenerative medicine has the potential to result in health and economic benefits, this relatively new field faces unique manufacturing and regulatory challenges in the development of novel therapies that are both safe and effective. Some of these issues arise because regenerative medicine therapies produce and rely on living cells and tissues, which are inherently variable, even within a single type of cell. On June 26, 2017, the Forum on Regenerative Medicine hosted a public workshop to examine and discuss challenges, opportunities, and best practices associated with defining and measuring the quality of cell and tissue products and raw materials in the research and manufacturing of regenerative medicine therapies. Workshop participants were asked to explore what measurements, characteristics, and technologies may be important in the development of safe and effective new products and therapies. This proceedings is a summary of the workshop.